Messages - Merdan

Good morning!I've been using this wonderful app for about a year and recommended it to my colleagues who where really surprised and thankful. But, this september i had a crash and the app returned to the very first screen, I mean it asked my to sign in. I've been trying to sign in since September but unfortunately nor the app neither the website can't solve this issue. I would be grateful if you have any solutions.Thx in advance.